Factory automation (FA) systems that use industrial robots to achieve unattended operations of operations that were used to be performed by workers and accordingly make improvements in redaction of errors in works made by workers, in working efficiency, and in the safety of workers are used in many work sites.
In an FA system, in an assembling process consisting of repeated works done by a robot, for example, the effect of a slight difference in the positions in which parts to be assembled are set or the handling posture of the robot may feed through to the following assembling work and thus trigger occurrence of non-conforming products.
For this reason, the manager of the FA system takes measures not to cause non-conforming products by regularly inspecting the operation of each robot and the positions in which parts to be assembled are set, etc.
Patent Document 1: Japanese Laid-open Patent Publication No. 2007-334756
Patent Document 2: Japanese Laid-open Patent Publication No. 2006-79272
Patent Document 3: Japanese Laid-open Patent Publication No. 2006-178790
The above-described conventional technology however has a problem in that it is not possible to accurately detect abnormality due to a variance in the work of a robot that causes non-conforming products.
For example, in the conventional FA system, the manager takes measures by regularly inspecting the operations of each robot and the positions in which members to be assembled are set; however, it is difficult to manually find a slight variance in the work. Abnormality due to a variance in the work has an effect on the product being assembled and therefore it is preferable that a variance in the work be detected on site; however, it difficult to detect such a variance as described above and thus only what can be done conventionally is to estimate whether there was a variance in the work from the result of examining whether a product is a conforming product or a non-conforming product after the product is assembled. The problem is not limited to robots and occurs similarly in the case where abnormality of a subject that does a given work is detected.